Reusable high performance water based drilling fluids

ABSTRACT

A method for drilling a borehole includes, while drilling, circulating a fluid composition. The fluid composition includes an aqueous continuous phase comprising an additive composition, the additive composition comprising an amphoteric polymer, a polyacrylamide, or a combination thereof; and an organic internal phase comprising a glycerol, a polyglycerol, a poly hydroxyl alcohol, a monosaccharide derivative, a polysaccharide derivative, or a combination thereof. In one embodiment, the additive composition includes a salt up to saturation and at least one of an amphoteric polymer or a polyacrylamide. In another embodiment, the additive composition includes a hydratable polymer, and an amphoteric polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 14/506,137, filed Oct. 3, 2014, which claims the benefit ofUnited Application Ser. No. 61/888,325, filed Oct. 8, 2013, each ofwhich is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

Embodiments of this present disclosure generally relate to reusable highperformance water based drilling fluids and methods of using water baseddrilling fluids.

In particular, embodiments of this invention relates to reusable highperformance water based drilling fluids, and methods of use thereof,where the fluids include a water based continuous aqueous phase anddiscontinuous non-aqueous phase, where the aqueous phase is a brine andthe non-aqueous phase is composed of glycerols, polyglycerols, polyhydroxyl alcohols, poly hydroxyl alcohols, monosaccharide derivatives,polysaccharide derivatives, or mixtures and combinations thereof.

2. Description of the Related Art

Oil based drilling fluids have historically been the preferred choicefor exploration and development of drilling projects. These fluids areoften reused from well to well and guarantee among other things:reasonable costs, good inhibiting properties, and good lubricityproperties. Against these advantages, there are several disadvantagesincluding high environmental impact such as spillage risks, significantcuttings disposal costs and location remedial costs. These fluids alsoentail logistics issues in moving large volumes of organic base fluidsand salts, increased costs on solids control equipments and anundesirable dependency on the type of organic base fluids chosen for agiven project.

Many principles have been addressed to control shale hydration due todrilling fluids used in the oil industry. Some of these controltechnologies include the use of lime and gypsum calcic fluids, saltsdissolved in the aqueous phase up to saturation, silicate fluids, shaleencapsulating polymers, amines, amphoteric polymers, inverted emulsionfluids, pore pressure transmission blocking mechanisms, glycol basedfluids and many intermediate combinations of the above. Most fluids arebased on one principle and often fail to address geological conditionsand environmental regulation.

Historically, water based fluids have been a one interval disposablevolume. Thus, there is a need in the art for reusable high performancewater based drilling fluids.

SUMMARY

In an embodiment is provided a method for drilling a borehole comprisingcirculating, e.g., in the borehole, a composition. The compositionincludes an aqueous continuous phase comprising an additive composition,the additive composition comprising an amphoteric polymer, apolyacrylamide, or a combination thereof; and an organic internal phasecomprising a glycerol, a polyglycerol, a poly hydroxyl alcohol, amonosaccharide derivative, a polysaccharide derivative, or a combinationthereof.

In another embodiment is provided a method for drilling a boreholecomprising circulating, e.g., in the borehole, a composition. Thecomposition includes an aqueous continuous phase comprising an additivecomposition, the additive composition comprising a salt up to saturationand at least one of an amphoteric polymer or a polyacrylamide; and anorganic internal phase comprises a glycerol, a polyglycerol, a polyhydroxyl alcohol, a monosaccharide derivative, a polysaccharidederivative, or a combination thereof.

In another embodiment is provided a method for drilling a boreholecomprising circulating, e.g., in the borehole, a composition. Thecomposition includes an aqueous continuous phase comprising an additivecomposition, the additive composition comprising a salt up tosaturation, a hydratable polymer, and an amphoteric polymer; and anorganic internal phase comprising a glycerol, a polyglycerol, a polyhydroxyl alcohol, a monosaccharide derivative, a polysaccharidederivative, or a combination thereof.

In another embodiment is provided different inhibition mechanisms tocope with reactive formations such as a formation including swellableclays. The present compositions emulate oil based fluids by having anorganic internal phase, which creates an osmotic membrane. The osmoticmembrane allows hydration-dehydration mechanisms to be in place andcontrol interactions between the formation and the fluid. Thenon-aqueous phase, on the inhibition side, comprises or is composed ofglycerols, polyglycerols, poly hydroxyl alcohols, monosaccharidederivatives, polysaccharide derivatives, or mixtures and combinationsthereof, while the aqueous phase contains ingredients to impartdifferent inhibiting mechanisms to the overall composition, where theingredients and/or mechanisms include, without limitation, amphotericpolymers, potassium and/or sodium salts of up to saturation and/orpolyacrylamides. In certain embodiments, the compositions may alsoinclude silicates. The compositions of this invention allow the drilledcuttings to travel up the annular gap, avoiding dissolution. Also fluiddilution is minimized. Pore pressure transmission blocking mechanismsare present in the fluids enhancing well stability and widening thepressure window between hydrostatic pressure and fracture gradient. Thefluids have low environmental impact, which will save on solids controlequipment requirements and will minimize disposal and remedial costs.

In another embodiment is provided methods for making or preparingcompositions of this present disclosure.

In another embodiment is provided provide reusable high performancewater based drilling fluids and other reusable high performance waterbased downhole fluids having low toxicity and reduced environmentalimpact. This reduces operating costs by improving material logistics andproviding high drilling performance to operators.

DETAILED DESCRIPTION

The inventors have found that a reusable high performance water basedfluids may be formulated having a full range of densities. The reusablehigh performance water based fluids include a continuous aqueous phaseand a discontinuous organic or non-aqueous phase forming an osmoticmembrane. The aqueous phase comprises a brine having certain controlledproperties and the non-aqueous phase comprises glycerols, polyglycerols,poly hydroxyl alcohols, monosaccharide derivatives, polysaccharidederivatives, or mixtures and combinations thereof. The term reusable, inthe context of oil-based drilling muds or fluids, means that when aparticular drilling job is finished or completed, the mud or drillingfluid may be stored in tanks until it is needed for drilling anotherwell. The fluids of the present disclosure remain complete, highperformance water based drilling fluids that may be used over and overagain for drilling. The drilling fluids of the present disclosure,therefore, are capable of being used from job to job, with make-up fluidvolume being added as needed and drilling fluid treatments made to thedrilling fluids of the present disclosure to maintain, modify, and/oralter desired fluid properties.

The inventors have found that by using a storage facility nearby thelocation in between jobs, the water based fluid may be renderedreusable. The present fluids will reduce liability for environmentalintegrated projects.

The inventors have also found that reusable high performance water basedfluids may be formulated having density over a wide density range. Incertain embodiments, the density of the fluids ranges between about 8.6ppg and one 20 ppg and the fluids may be formulated for both low,moderate, and high temperature applications. In certain embodiments, thedensity of the fluids is between about 8.6 ppg and 18 ppg. In otherembodiments, the density of the fluids is between about 8.6 ppg and 16ppg. In other embodiments, the density of the fluids is between about8.6 ppg and 14 ppg. In other embodiments, the density of the fluids isbetween about 8.6 ppg and 12 ppg. In other embodiments, the density ofthe fluids is between about 8.6 ppg and 10 ppg. The term “ppg” will beherein understood to mean “pounds per gallon”.

Multi-functional additives have been developed that improve drillingfluid lubricity as well as a penetration rate and improve inhibitingproperties of reactive shale. The new additives have been used atvarious volume % (vol. %) concentrations, based on the total fluidcomposition, e.g., drilling fluid composition, in formulations havingvarying densities. In certain embodiments, the concentration is at least5% by volume. In certain embodiments, the concentration is at least 10%by volume. In certain embodiments, the concentration is at least 16% byvolume. In certain embodiments, the concentration is at least 18% byvolume. In certain embodiments, the concentration is up to 20% byvolume.

In certain embodiments, the compositions include from about 51 wt. % toabout 95 wt. % of the aqueous phase and from about 5 wt. % to about 49wt. % of the non-aqueous phase. In other embodiments, the compositionsinclude from about 55 wt. % to about 95 wt. % of the aqueous phase andfrom about 5 wt. % to and about 45 wt. % of the non-aqueous phase. Inother embodiments, the compositions include from about 60 wt. % to about95 wt. % of the aqueous phase and from about 5 wt. % to and about 40 wt.% of the non-aqueous phase. In other embodiments, the compositionsinclude from about 65 wt. % to about 95 wt. % of the aqueous phase andfrom about 5 wt. % to and about 35 wt. % of the non-aqueous phase. Inother embodiments, the compositions include from about 75 wt. % to about95 wt. % of the aqueous phase and from about 5 wt. % to about 25 wt. %of the non-aqueous phase.

Embodiments of the present disclosure broadly relate to reusable fluidcompositions including (a) an aqueous continuous phase including anadditive composition to change certain properties of the aqueouscontinuous phase, where the additive composition comprises amphotericpolymers, salts up to saturation, polyacrylamides, and mixtures orcombinations thereof, and (b) an organic internal phase includingglycerols, polyglycerols, poly hydroxyl alcohols, monosaccharidederivatives, polysaccharide derivatives, or mixtures and combinationsthereof, where the organic internal phase forms an osmotic membranewithin the continuous aqueous phase and where the osmotic membraneallows hydration-dehydration mechanisms to be in place and controlinteractions between formation and fluid. In other embodiments, theadditive composition includes hydratable polymers. In other embodiments,the additive composition includes a humalite product, high molecularweight xanthan gum and/or a complex mixture of natural polysaccharides,high-quality, low-viscosity, sodium salt of carboxymethyl celluloses,polyanionic cellulose, glycol-based anti-foaming agents, white calciumcarbonate, barium sulfate mineral, and/or shale inhibitor. Humalite maybe described as a natural derivative from sub-bituminous coal,containing substances such as humic acid, fulvic acid and/or humin. Inother embodiments, the compositions have a density between about 8.6 ppgand about 20 ppg. In other embodiments, the compositions have a densitybetween about 8.6 ppg and about 18 ppg. In other embodiments, theaqueous phase is present in an amount between about 51 wt. % and about95 wt. % and the non-aqueous phase is present in an amount between about5 wt. % and about 49 wt. %. In other embodiments, the aqueous phase ispresent in an amount between about 55 wt. % and about 95 wt. % and thenon-aqueous phase is present in an amount between about 5 wt. % andabout 45 wt. %. In other embodiments, the aqueous phase is present in anamount between about 65 wt. % and about 95 wt. % and the non-aqueousphase is present in an amount between about 5 wt. % and about 35 wt. %.In other embodiments, the aqueous phase comprises a brine. In otherembodiments, the brine comprises a fresh water brine formed by addingthe salts to fresh water.

Embodiments of the present disclosure broadly relates to reusabledrilling fluid compositions including (a) an aqueous continuous phaseincluding an additive composition to change certain properties of theaqueous continuous phase, where the additive composition includesamphoteric polymers, salts up to saturation, polyacrylamides, ormixtures and combinations thereof, and (b) an organic internal phaseincluding glycerols, polyglycerols, poly hydroxyl alcohols,monosaccharide derivatives, polysaccharide derivatives, or mixtures andcombinations thereof, where the organic internal phase creates anosmotic membrane within the continuous aqueous phase and where theosmotic membrane allows hydration-dehydration mechanisms to be in placeand control interactions between formation and fluid. In certainembodiments, the compositions have a density between about 8.6 ppg andabout 20 ppg. In other embodiments, the compositions have a densitybetween about 8.6 ppg and about 18 ppg. In other embodiments, theaqueous phase is present in an amount between about 51 wt. % and about95 wt. % and the non-aqueous phase is present in an amount between about5 wt. % and about 49 wt. %. In other embodiments, the aqueous phase ispresent in an amount between about 55 wt. % and about 95 wt. % and thenon-aqueous phase is present in an amount between about 5 wt. % andabout 45 wt. %. In other embodiments, the aqueous phase is present in anamount between about 65 wt. % and about 95 wt. % and the non-aqueousphase is present in an amount between about 5 wt. % and about 35 wt. %.In other embodiments, the aqueous phase comprises a brine. In otherembodiments, the brine comprises a fresh water brine formed by addingthe salts to fresh water.

Embodiments of the present disclosure broadly relates to methods fordrilling a borehole including the step of (a) while drilling,circulating a fluid composition of the present disclosure. The fluidcomposition comprises (a) an aqueous continuous phase including anadditive composition to change certain properties of the aqueouscontinuous phase, where the additive composition comprises amphotericpolymers, salts up to saturation, polyacrylamides or mixtures andcombinations thereof, and (b) an organic internal phase includingglycerols, polyglycerols, poly hydroxyl alcohols, monosaccharidederivatives, polysaccharide derivatives, or mixtures and combinationsthereof, where the organic internal phase creates an osmotic membranewithin the continuous aqueous phase, where the osmotic membrane allowshydration-dehydration mechanisms to be in place and control interactionsbetween formation and fluid and where the drilling fluid composition isreusable and the fluid has improved lubricity and improved cutting liftproperties. In certain embodiments, the compositions have a densitybetween about 8.6 ppg and about 20 ppg. In other embodiments, thecompositions have a density between about 8.6 ppg and about 18 ppg. Inother embodiments, the aqueous phase is present in an amount betweenabout 51 wt. % and about 95 wt. % and the non-aqueous phase is presentin an amount between about 5 wt. % and about 49 wt. %. In otherembodiments, the aqueous phase is present in an amount between about 55wt. % and about 95 wt. % and the non-aqueous phase is present in anamount between about 5 wt. % and about 45 wt. %. In other embodiments,the aqueous phase is present in an amount between about 65 wt. % andabout 95 wt. % and the non-aqueous phase is present in an amount betweenabout 5 wt. % and about 35 wt. %. In other embodiments, the aqueousphase comprises a brine. In other embodiments, the brine comprises afresh water brine formed by adding the salts to fresh water.

Suitable Reagents

Suitable non-aqueous phase compositions include, without limitation,polyglycerol blends. Exemplary examples include a specific commercialmixture of mono, di, and triglycerins or a polyglycerol blend such asOxi-Cure products from Cargill, Incorporated including Oxi-Cure 500bearing CAS #25618-55-7 with synonymous products including glycerolhomopolymers, glycerol polymers, polyglycerols, and/or1,2,3-propanetriol homopolymers. One polyglycerol blend used in thecompositions of the present disclosure had the following specification:

Structure HO(CH₂CH(OH)CH₂O)_(n)H Structure HO(CH₂ CH(CH₂OH)O)_(n)H Mol.Formula HO(C₃H₆O₂)_(n)H Test Specification Appearance Pale yellow stickyliquid Water ≤1% Viscosity ~41 Pa · s (dynamic) Assay (glpc) TriglycerolFrom 35 wt. % to 55 wt. % Diglycerol from 15 wt. % to 30 wt. %Tetraglycerol from 10 wt. % to 25 wt. % Pentaglycerol less than or equalto (≤) 10 wt. % Higher oligomers less than or equal to (≤) 5 wt. % RI,ηD^(20° C.) 1.491 @ 25° C. Heavy metals less than (<) 10 ppm As lessthan (<) 3 ppm Chloride less than (<) 0.1%

Suitable aqueous phase compositions include, without limitation, sodiumbrines, potassium brines, calcium brines, other brines, or mixtures andcombinations thereof. The brines are made by adding sodium, potassium,and/or calcium salts to water up to saturation. Exemplary examples ofsodium, potassium, and/or calcium salts include NaCl, KCl, CaCl₂, and/orequivalent sodium, potassium and/or calcium salts.

Suitable polyols, monosaccharides, and/or polysaccharides include,without limitation, six carbon sugars and their derivatives (e.g.,allose, altrose, glucose, mannose, gulose, idose, galactose, talose, andcyclic hemiacetals or other derivatives), sorbitol, sorbitan, agar,agarose, alginic acid, alguronic acid, alpha glucan, amylopectin,amylose, arabinoxylan, beta-glucan, biocell collagen, callose, capsulan,carrageenan, cellodextrin, cellulin, cellulose, chitin, chitinnanofibril, chitosan, chrysolaminarin, curdlan, cyclodextrin,deae-sepharose, dextran, dextrin, exopolysaccharide, alpha-cyclodextrin,ficoll, fructan, fucoidan, galactoglucomannan, galactomannan, gellangum, glucan, glucomannan, glucuronoxylan, glycocalyx, glycogen,hemicellulose, homopolysaccharide, hypromellose, icodextrin, inulin,kefiran, laminarin, lentinan, levan polysaccharide, lichenin, matrixdb,mixed-linkage glucan, mucilage, natural gum, oxidized cellulose,paramylon, pectic acid, pectin, pentastarch, pleuran, polydextrose,polysaccharide peptide, porphyran, pullulan, schizophyllan, selectiverelaxant binding agent, sepharose, sinistrin, sizofiran, sugammadex,unhydrolysable glucose polymers, welan gum, xanthan gum, xylan,xyloglucan, zymosan or mixtures or combinations thereof.

Suitable hydratable polymers that may be used in embodiments of thepresent disclosure include any of the hydratable polysaccharides whichare capable of forming a gel in the presence of a crosslinking agent.For instance, suitable hydratable polysaccharides include, but are notlimited to, xanthan gums, galactomannan gums, glucomannan gums, guars,derived guars, and cellulose derivatives. Specific examples are guargum, guar gum derivatives, locust bean gum, Karaya gum, carboxymethylcellulose, carboxymethyl hydroxyethyl cellulose, and hydroxyethylcellulose. Exemplary examples include, but are not limited to, guargums, hydroxypropyl guar, carboxymethyl hydroxypropyl guar,carboxymethyl guar, and carboxymethyl hydroxyethyl cellulose. Suitablehydratable polymers may also include synthetic polymers, such aspolyvinyl alcohol, polyacrylamides, poly-2-amino-2-methyl propanesulfonic acid, and various other synthetic polymers and copolymers. Thehydratable polymer may be present in the fluid in concentrations rangingfrom about 0.10% to about 5.0% by weight of the aqueous fluid. Apreferred range for the hydratable polymer is about 0.20% to about 0.80%by weight.

Suitable amphoteric polymers include, without limitation, branchedand/or cross-linked associative amphoteric polymers. The usablebranching agents (cross-linking agents) are N-methylol acrylamide,methylene bis acrylamide, allyl ethers of sucrose, diacrylates, divinylsand all other multifunction compounds which can cause branching. Onecould also use one of the known branching agents for diallylatedcompounds such as methyl triallyl ammonium chloride, triallylamine,tetraallyl ammonium chloride, tetra allyl oxyethane, tetra allylethylene diamine and, more generally, all polyallylated compounds. It isalso possible to make post-cross-linked polymers, for example byamidation reaction, esterification reaction, gamma ray treatment, etc.

An example of an amphoteric polymer is described in U.S. Pat. No.7,700,702 B2. An example of such amphoteric polymer may comprise atleast one acrylamide-derived cationic monomer containing a hydrophobicchain and with the general formula:R1,R₂C═CR₃CONR⁴QN⁺R⁵R⁶R⁷X⁻where: R¹, R², R³, R⁴, R⁵, and R⁶ are independently, a hydrogen or analkyl chain containing 1 to 4, carbons, Q is an alkyl chain containing 1to 8 carbons, R⁷ is an alkyl or arylalkyl chain containing 8 to 30carbons, X is a halide selected from the group including bromide,chloride, iodide, fluoride or a counterion with a negative charge;

between 1 and 99.9 mole % of at least one anionic monomer, and

between 1 and 99 mole % at least one non-ionic hydrosoluble monomer.

The anionic monomers can be selected from a wide group. These monomersmay present acrylic, vinyl, maleic, fumaric or allyl functionalities andmay contain a carboxy, phosphonate, sulfonate or other group with ananionic charge, or the ammonium salt or alkaline-earth metal salt oralkaline metal salt corresponding to such a monomer. Examples ofsuitable monomers include acrylic acid, methacrylic acid, itaconic acid,crotonic acid, maleic acid, fumaric acid and strong-acid monomers, forexample with a sulfonic or phosphonic acid-type function such as2-acrylamido-2-methylpropane sulfonic acid, vinylsulfonic acid,vinylphosphonic acid, allylsulfonic acid, allylphosphonic acid, styrenesulfonic acid and their water-soluble salts of an alkali metal,alkaline-earth metal and ammonium.

The at least one non-ionic hydrosoluble monomer can be selected from thegroup including water-soluble vinyl monomers. In certain embodiments,the monomers belonging to this category are advantageously selected fromthe group including acrylamide and methacrylamide,N-isopropylacrylamide, N,N-dimethylacrylamide and N-methylolacrylamide.N-vinylformamide, N-vinyl acetamide, N-vinylpyridine and/orN-vinylpyrrolidone can also be used. Acrylamide may be the preferrednon-ionic monomer.

Other amphoteric polymers include polymers having between 0.005 and 10mole % hydrophobic cationic monomers, between 5 and 90 mole % of atleast one anionic monomer, advantageously acrylic acid and/ormethacrylic acid and/or 2-acrylamido-2-methylpropane sulfonic acid andtheir salts; and between 5 and 90 mole % of at least one hydrosolublenon-ionic monomer, advantageously acrylamide and/or methacrylamideand/or N-isopropylacrylamide and/or N,N-dimethylacrylamide and/orN-vinylformamide and/or N-vinyl acetamide and/or N-vinylpyrrolidone.Other polymers contain between 0.01 and 5 mole % of hydrophobic monomersand between 10 and 60 mole % of an anionic monomer and between 35 and 90mole % of a non-ionic monomer. Other polymers contain between 0.02 and 2mole % of hydrophobic monomers and between 10 and 50 mole % of ananionic monomer: acrylic acid, methacrylic acid and/or2-acrylamido-2-methylpropane sulfonic acid and their salts, and between48 and 90 mole % of a non-ionic monomer: acrylamide and/ormethacrylamide and/or N-isopropylacrylamide and/orN,N-dimethylacrylamide and/or N-vinylformamide and/or N-vinyl acetamideand/or N-vinylpyrrolidone. Other polymers include acrylamide-derivedhydrophobic cationic monomers preferred for the present disclosure areN-acrylamidopropyl-N,N-dimethyl-N-dodeyl ammonium chloride (DMAPACl(C₁₂)), N-methacrylamidopropyl-N,N-dimethyl-N-dodecyl ammoniumchloride (DMAPMA Cl(C₁₂)), N-acrylamidopropyl-N,N-dimethyl-N-dodecylammonium bromide (DMAPA Br(C₁₂)),N-methacrylamidopropyl-N,N-dimethyl-N-dodecyl ammonium bromide (DMAPMABr(C₁₂)), N-acrylamidopropyl-N,N-dimethyl-N-octadecyl ammonium chloride(DMAPA Cl(C₁₈)), N-methacrylamidopropyl-N,N-dimethyl-N-octadecylammonium chloride (DMAPMA Cl(C₁₈)),N-acrylamidopropyl-N,N-dimethyl-N-octadecyl ammonium bromide (DMAPABr(C₁₈)), N-methacrylamidopropyl-N,N-dimethyl-N-octadecyl ammoniumbromide (DMAPMA Br(C₁₈)).

Suitable silicates that may be used in the fluids of the presentdisclosure include, without limitation, hydrated or anhydrous silicateminerals with a layered structure and include, for example,alumino-silicate clays such as kaolins including hallyosite, smectitesincluding montmorillonite, illite, and the like. Exemplary silicatesinclude those marketed under the tradename CLOISITE® marketed bySouthern Clay Additives, Inc. In an embodiment, silicates are exfoliatedto separate individual sheets, or are non-exfoliated. Other silicates ofsimilar structure can also be included such as, for example, talc, micasincluding muscovite, phlogopite, or phengite, or the like.

EXPERIMENTS Example 1

This example illustrates the preparation of reusable high performancewater based drilling fluid having a density of 10 ppg.

18.0 wt. % of sorbitol powder was dissolved in 23.3 wt. % deionizedwater. The resulting aqueous solution was then mixed into 56.7 wt. % ofa polyglycerol blend such as Oxi-Cure 500 and mixing was continued untilfluid was completely blended. To this fluid, 2.0 wt. % of a 50 wt. % KOHsolution (1.0% equivalent KOH) was added. The KOH was added to the 13.1wt. % NaCl brine, then pre-solubilize the 10 ppb HUMALITE in the aqueousmixture. The resulting polyglycerol blend was used successfully at a 14%concentration level in 10 ppg and 12 ppg formulations of a 13.1% byweight NaCl water-base system. The initial pH was 12.34 at 72.2° F. ThepH after 30 days was 11.22 at 71.0° F. The pH after 71 days was 9.84 at71.0° F.

The neat composition of Example 1 was a viscous liquid and had abrownish amber color, a specific gravity between 1.23 and 1.28, adensity in pounds per gallon (ppg) between 10.26 ppg and 10.68 ppg, aflash point >392° F. (>200° C.), a pH between 9.5 and 10.5, mild odor,and freeze point <−36.4° F. (<−38° C.).

TABLE 1 Composition of the Example 1 FORMULATION SP. GR. GRAMS WT. %Aqueous Component 86.00 13.1 wt. % NaCl 1.09 297.52 brine, ppb KOH, ppb2.06 1.50 WRD-6003, ppb 1.30 1.50 Wel-Zan D, ppb 1.55 1.50 Wel-Pac LV,ppb 1.60 4.00 Wel-Defoam G, ppb 2 drops ExCAL CW 325 ppb 2.70 20.00Barite, ppb 4.20 10.70 KCI, ppb 1.98 14.00 Wel-Hib NPH, ppb 1.07 8.00Non-Aqueous Component 14.00 Polyglycerol blend* 1.26 53.81 Total Weight(g) 419.53 Total Volume 350.00 (cc) WBM Weight 10.00 (ppg) SG 1.199WRD-6003 is a humalite product available from Canadian HumaliteInternational Inc. Wei-Zan ™ D—high molecular weight xanthan gum, acomplex mixture of natural polysaccharides available from Weatherford.Wei-Pac ™ LV—high-quality, low-viscosity, sodium salt of carboxymethylcellulose-commonly referred to as polyanionic cellulose available fromWeatherford. Wel-Defoam ™ G—a glycol-based anti-foaming agent formulatedfor use in polymer systems available from Weatherford. EwxCal—whitecalcium carbonate 325 mesh available SpecialChem Barite—barium sulfatemineral Wel-Hib NPH a shale inhibitor available from Weatherford.Polyglycerol blend* was Oxi-cure 500 from Cargill, Inc.

TABLE 2 Example 1 Selected Properties OFI# Rheology at Cell# 120° F.After Hot Before Hot Rolling Property Rolling at 250° F. 600 rmp 98 92300 rmp 61 59 200 rmp 47 45 100 rmp 29 28  6 rmp 4 5  3 rmp 3 4 10″Second Gel 2 4 10′ Minute Gel 3 5 PV, cp 37 33 YP, lb/100 ft² 24 26 APIFluid Loss, mL 2.5 HTHP Fluid Loss at 250° F., mL 13.6 pH 10.8 @ 68.5°F. 9.25 @ 70.8° F. Mud Weight, ppg 10.09 10.01 Specific Gravity 1.211.20

Example 1 had a pH: 13.17 @ 68.8° F., a specific gravity of 1.24, and abrownish amber color. The freezing point of the composition was supposedto be −38° F. When the sample was left in the chiller for 24 hours at−38° F., the sample was very thick with very slow flow fluid, but wasnot frozen. When the sample was left for 48 hours at −38° F., the samplewas still was very thick with very slow flow, but still not frozen.After sitting at room temperature for about 7 minutes to 8 minutes afterbeing left in the chiller for 48 hours, the sample was back to flowingthe same as the 0° F. After the sample was in the chiller for 24 hoursat 0° F., the sample was normal. After the sample was in the chiller for24 hours at −20° F., the sample was very thick and very slow flow.

Example 2

This example illustrates reusable high performance water based fluidhaving a density of 12.80 ppg. This fluid was prepared in accord withthe preparation method of Example 1.

TABLE 4 Composition of the Example 2 FORMULATION SP. GR. GRAMS WT %Aqueous Component 86.0 13.1 wt. % NaCl 1.09 272.40 brine, ppb KOH, ppb2.06 1.00 WRD-6003, ppb 1.30 10.00 Wel-Zan D, ppb 1.55 0.75 Wel-Pac LV,ppb 1.60 3.25 Wel-Defoam G, ppb 2 drops ExCAL CW 325 ppb 2.70 20.00Barite, ppb 4.20 125.50 KCI, ppb 1.98 14.00 Wel-Hib NPH, ppb 1.07 8.00Non-Aqueous Component 14.00 Polyglycerol blend* 1.26 48.48 Total Weight(g) 503.38 Total Volume 350.00 (cc) WBM Weight 12.00 (ppg) SG 1.438WRD-6003 is a humalite product available from Canadian HumaliteInternational Inc. Wei-Zan ™ D—high molecular weight xanthan gum, acomplex mixture of natural polysaccharides available from Weatherford.Wei-Pac ™ LV—high-quality, low-viscosity, sodium salt of carboxymethylcellulose-commonly referred to as polyanionic cellulose available fromWeatherford. Wel-Defoam ™ G—a glycol-based anti-foaming agent formulatedfor use in polymer systems available from Weatherford. EwxCal—whitecalcium carbonate 325 mesh available SpecialChem Barite—barium sulfatemineral Wel-Hib NPH a shale inhibitor available from Weatherford.Polyglycerol blend* was Oxi-cure 500 from Cargill, Inc.

TABLE 5 Example 2 Selected Properties OFI# Rheology at Cell# 120° F.After Hot Before Hot Rolling Property Rolling at 250° F. 600 rmp 146 141300 rmp 98 94 200 rmp 81 74 100 rmp 51 48  6 rmp 7 10  3 rmp 6 7 10″Second Gel 6 8 10′ Minute Gel 7 10 PV, cp 48 47 YP, lb/100 ft² 50 47 APIFluid Loss, mL #3 1.9 HTHP Fluid Loss at 250° F., mL 15.2 pH 10.3 @ 74°F. 8.45 @ 72° F. Mud Weight, ppg 12.18 12.01 Specific Gravity 1.46 1.44

All documents described herein are incorporated by reference herein,including any priority documents and/or testing procedures to the extentthey are not inconsistent with this text. Further, all documents andreferences cited herein, including testing procedures, publications,patents, journal articles, etc. are herein fully incorporated byreference for all jurisdictions in which such incorporation is permittedand to the extent such disclosure is consistent with the description ofthe present disclosure. As is apparent from the foregoing generaldescription and the specific embodiments, while forms of the embodimentshave been illustrated and described, various modifications can be madewithout departing from the spirit and scope of the present disclosure.Accordingly, it is not intended that the present disclosure be limitedthereby. Likewise, the term “comprising” is considered synonymous withthe term “including.” Likewise whenever a composition, an element or agroup of elements is preceded with the transitional phrase “comprising,”it is understood that we also contemplate the same composition or groupof elements with transitional phrases “consisting essentially of,”“consisting of,” “selected from the group of consisting of,” or “I”preceding the recitation of the composition, element, or elements andvice versa, e.g., the terms “comprising,” “consisting essentially of,”“consisting of” also include the product of the combinations of elementslisted after the term.

For the sake of brevity, only certain ranges are explicitly disclosedherein. However, ranges from any lower limit may be combined with anyupper limit to recite a range not explicitly recited, as well as, rangesfrom any lower limit may be combined with any other lower limit torecite a range not explicitly recited, in the same way, ranges from anyupper limit may be combined with any other upper limit to recite a rangenot explicitly recited. Additionally, within a range includes everypoint or individual value between its end points even though notexplicitly recited. Thus, every point or individual value may serve asits own lower or upper limit combined with any other point or individualvalue or any other lower or upper limit, to recite a range notexplicitly recited.

We claim:
 1. A method for drilling a borehole, comprising: whiledrilling, circulating a fluid composition comprising: an aqueouscontinuous phase comprising an additive composition, the additivecomposition comprising an amphoteric polymer, a polyacrylamide, or acombination thereof; and an organic internal phase comprising aglycerol, a polyglycerol or a combination thereof.
 2. The method ofclaim 1, wherein the organic internal phase further comprises a polyhydroxyl alcohol, a monosaccharide derivative, or a combination thereof.3. The method of claim 1, wherein the fluid composition has a densitybetween about 8.6 ppg and about 20 ppg, the aqueous continuous phase ispresent in an amount between about 51 wt. % and about 95 wt. %, and theorganic internal phase is present in an amount between about 5 wt. % andabout 49 wt. %.
 4. The method of claim 1, wherein the fluid compositionhas a density between about 8.6 ppg and about 16 ppg, the aqueouscontinuous phase is present in an amount between about 55 wt. % andabout 95 wt. %, and the organic internal phase is present in an amountbetween about 5 wt. % and about 45 wt. %.
 5. The method of claim 1,wherein the fluid composition has a density between about 8.6 ppg andabout 14 ppg, the aqueous continuous phase is present in an amountbetween about 65 wt. % and about 95 wt. %, and the organic internalphase is present in an amount between about 5 wt. % and about 35 wt. %.6. The method of claim 1, wherein the aqueous continuous phase furthercomprises a brine, the brine comprises a salt, and the salt comprises asodium salt, a potassium salt, a calcium salt, or a combination thereof.7. The method of claim 6, wherein the brine comprises a fresh waterbrine and wherein the salt comprises NaCl, KCl, CaCl₂), an equivalentsalt, or a combination thereof.
 8. A method for drilling a borehole,comprising: while drilling, circulating a fluid composition comprising:an aqueous continuous phase comprising an additive composition, theadditive composition comprising a salt up to saturation and at least oneof an amphoteric polymer or a polyacrylamide; and an organic internalphase comprising a glycerol, a polyglycerol, or a combination thereof.9. The method of claim 8, wherein the organic internal phase furthercomprises a poly hydroxyl alcohol, a monosaccharide derivative, or acombination thereof.
 10. The method of claim 8, wherein the fluidcomposition has a density between about 8.6 ppg and about 20 ppg, theaqueous continuous phase is present in an amount between about 51 wt. %and about 95 wt. %, and the organic internal phase is present in anamount between about 5 wt. % and about 49 wt. %.
 11. The method of claim8, wherein the fluid composition has a density between about 8.6 ppg andabout 16 ppg, the aqueous continuous phase is present in an amountbetween about 55 wt. % and about 95 wt. %, and the organic internalphase is present in an amount between about 5 wt. % and about 45 wt. %.12. The method of claim 8, wherein the fluid composition has a densitybetween about 8.6 ppg and about 14 ppg, the aqueous continuous phase ispresent in an amount between about 65 wt. % and about 95 wt. %, and theorganic internal phase is present in an amount between about 5 wt. % andabout 35 wt. %.
 13. The method of claim 8, wherein the salt comprises asodium salt, a potassium salt, a calcium salt, or a combination thereof.14. The method of claim 13, wherein the salt comprises NaCl, KCl,CaCl₂), an equivalent salt, or a combination thereof.
 15. A method fordrilling a borehole, comprising: while drilling, circulating a fluidcomposition comprising: an aqueous continuous phase comprising anadditive composition, the additive composition comprising a salt up tosaturation, a hydratable polymer, and an amphoteric polymer; and anorganic internal phase comprising a glycerol, a polyglycerol, or acombination thereof.
 16. The method of claim 15, wherein the organicinternal phase further comprises a poly hydroxyl alcohol, amonosaccharide derivative, or a combination thereof.
 17. The method ofclaim 15, wherein the salt is a potassium salt, a sodium salt, or acombination thereof.
 18. The method of claim 15, wherein the fluidcomposition has a density between about 8.6 ppg and about 20 ppg, theaqueous continuous phase is present in an amount between about 51 wt. %and about 95 wt. %, and the organic internal phase is present in anamount between about 5 wt. % and about 49 wt. %.
 19. The method of claim15, wherein the fluid composition has a density between about 8.6 ppgand about 16 ppg, the aqueous continuous phase is present in an amountbetween about 55 wt. % and about 95 wt. %, and the organic internalphase is present in an amount between about 5 wt. % and about 45 wt. %.20. The method of claim 15, wherein the fluid composition has a densitybetween about 8.6 ppg and about 14 ppg, the aqueous continuous phase ispresent in an amount between about 65 wt. % and about 95 wt. %, and theorganic internal phase is present in an amount between about 5 wt. % andabout 35 wt. %.